Upper Ovetian trilobites from Spain and their implications for the palaeobiogeography and correlation of the Cambrian Stage 3 in Gondwana

The upper part of the La Herrería Formation in Los Barrios de Luna (León Province, N Spain) has been revised from a palaeontological and biostratigraphical point of view. Two stratigraphic sections have been studied including their trilobite and ichnofossils contents. The ichnofossil assemblages have a high diversity of species characterising the Cruziana ichnofacies, suggesting a shallow sublittoral environment for the upper part of the La Herrería Formation. The trilobites species recognised are Lunagraulos antiquus, Dolerolenus formosus, Dolerolenus longioculatus, Lunolenus lunae, Metadoxides richterorum, Metadoxides armatus and Sardaspis? sp. from the upper Ovetian (lower Cambrian Stage 3 under discussion by the ISCS). The new trilobite assemblages make possible a good correlation between the lower Cambrian formations of North Spain, Sardinia, South China and Siberia. Analysis of the palaeobiogeographical meaning of all trilobite genera that have been identified in the upper Ovetian of Spain shows a strong connection between the northern peri-Gondwana margin and west Gondwana, with a low latitude distribution for the Spanish trilobites at this time.